Grinding tool



Nov. 29, 1938.

A. J. SIEVERS, JR

GRINDING TOOL Filed April 21, 1936 2 Shets-Sheet l r R2 2 n MM m We m 5 J Patented Nov. v29, 1938 UNITED STATES PATENT OFFICE GRINDING TOOL land, Calif.

Application April 21, 1936, Serial No. 75,514

6 Claims.

The invention relates to grinding tools and more particularly to such tools as are especially adapted for grinding cylindrical surfaces.

An object of the invention is to provide a device of the character described which is particularly adapted to grinding and truing the crank pins or throws of a crank shaft such as used in a reciprocating engine and to provide a device which may be so applied to a crank shaft without requiring the removal of the latter from its bearings in the engine.

Another object of the invention is to provide a grinding tool of the character above, which will be automatically self-adjustable and selfcentering and will maintain a uniform pressure of the grinding elements against the work and hold such elements in circular position relative to each other whereby, in truing out of round surfaces the grinding elements will be held away from the low spots", and in engagement substantially only with the high spots so as to bring the surface into substantially perfect roundness with a minimum removal of material.

A further object of the invention is to provide a device of the character described which may be readily and simply applied to a crank shaft as aforesaid, and will speedily true the crank pins to a desired finish with the exercise of but a minimum amount of work and skill on the part of the operator.

The invention possesses other objects and features of advantage, some of which, with the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description. may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings:

Figure 1 is a front elevation of the grinding tool constructed in accordance with the present invention;

Figure 2 is an end view of the apparatus shown in Figure 1;

Figures 3 and a. are longitudinal sectional views taken substantially on the planes of line 3--3 and 4-4.0f Figure 1;

Figure 5 is a front view showing the grinding face of one of the grinding elements;

Figure 6 is a transverse sectional view of the device and is taken substantially on the planes of lines a, b and c, as indicated on Figure 3.

The grinding tool of the present invention, and. as illustrated. in the accompanying drawings, comprises an annular member II which is arranged for positioning around an exterior surface I2 of a member I3 to be ground, and is provided with a plurality of grinding elements I4 for engagement with the surface I2. More especially the member II is composed of inner and outer annular sections I 6 and H, the former being slidably carried in an annular recess I8 provided in the member I1, and the member I6 is formed with radial and longitudinal guides or rails I9 and 2|, which are carried in grooves 22 and 23 in member I! for attaching the sections and enabling their relative circumferential displacement. Carried in a plurality of circum ferentially spaced radially extending recesses 24 in the inner member I6 are shanks or body portions 26 of the grinding elements I4, and the latter are formed inwardly on the inner periphery 21 of the sections I6 with a holder or head 28 having a plurality of abrasive blocks 29.

In accordance with the present invention the ring member II is centered about the surface I2 by the engagement therewith of the grinding elements, and with the elements so engaged the ring member is arranged to be rotated about the surface for grinding the same into a substantially true cylindrical form. Any suitable means may be used for rotating the ring member and, as here shown, the outer section I1 is provided with a circumferential groove 3| for the receipt of a driving belt 32. As a particularly important feature of the present device, the rotation of the same about the surface to be finished is caused to urge the grinding elements into engagement with the surface, whereby a constant pressure is uniformly applied to the elements and against the surface to be ground. In the present embodiment this force or pressure is derived from the provision of a plurality of spiral or cam grooves 33 provided in a radial surface 34 of the section I! abutting the section I6, and the adjacent sides 36 of the body portions 26 of the grinding elements are provided with pins 31 which are slidably carried in the grooves 33. As will be clear from the drawings, the grooves spiral inwardly in a contra-direction to that of the forced rotation of the outer section, whereby the reactive force on the inner section caused by the engagement of the grinding elements with the surface I2 will tend to hold the inner section against rotation with the outer section and thereby urge the inward extension of the grinding elements against the surface. Stated in another way, the forced rotation of the outer section with the elements in engagement with the surface I! establishes, due to the frictional drag of the elements I! against the surface and which drag is imparted to the inner section, a rotative forced diiferential which is translated by the engaged spiral grooves: 33 and the pins 31. to a radial force on the grinding elements.

In order that any variant in the rotative force applied to the outer section, such as caused by the whipping of the belt 32, or any nonuniformity in the output of the driving mechanism, shall not be translated into a corresponding variation in pressure of the elements against the surface 4 to be ground, a check mechanism is employed to prevent any retraction of the elements from the surface incident to a sudden decrease in the rotation force applied to the outer section. This means, as will be clear from Figure 6, comprises a ball check 38 which is carried in a bore 39 provided in the inner section l6 and which bore opens at an incline to the outer annular surface 4| defining the recess l8 in the outer section l1. Thus, with reference to Figure 6, it will be seen that on rotation of the member in a counterclockwise direction the ball 38 will be carried by centrifugal force into engagement with the surface 4|, but will allow a relative displacement between the inner and outer sections tending to tighten the grinding elements against the surface to be ground. However, should the rotative force applied to the outer section be, for any reason, momentarily decreased, the ball 38 will be immediately wedged between the surface 4| and the wall of the bore 39 to prevent any retractive displacement of the sections.

When the ring member is thereafter brought to a stop the ball 38 will drop to the bottom of the bore 39 and release the sections for relative displacement in either direction, and especially permit the retraction of the grinding ele ments from the surface to the ground. To facilitate the relative displacement of the sections the guide rail I 9 is provided over a portion of its periphery witha set of teeth 42, which are ar ranged for engagement with a pinion 43 provided on a key 44 and which pinion is extendable into an opening 46 provided in the front side of section I! in registration with a gear 42. Preferably the circumferential positioning of the teeth 42 and the opening 46 is such that with the opening in the lowermost position, as illustrated in Figures 1 and 6, the ball check 38 will rest at the bottom of the bore 39 and'away from engagement with the surface 4| of the outer section. e

As a most important feature of the present invention, the device has been especially adapted for use in connection with the grinding of the crank pins or throws of a crank shaft, such as of an ordinary reciprocating type internal combustion engine without requiring the removalof the shaft from its bearings .inthe engine. This has been provided for by constructing each ,ofthe sections it and i! of a pair of semi-circular segments 48, 49 and Si and 52, which maybe separated to assemblethering by halves around the crank pin to be. ground without requiring the movement of the grinding means over the ends of the crank shaft. Also, to permit the attachment of the belt 32 to the outer section without slipping the belt over the ends of the shaft the belt is provided with detachable ends (not shown). Any suitable means may be used for clamping the halves of the respective sections together and, as here illustrated, a pair of screws 53 connecting the abutting ends of the outer segments 5i and I! are used to hold the assembly together.

While the inner and outer sections are each formed of segments, as above explained, the adjacent ends of the segments are held in abutting relation when the unit is assembled to cause the inner and outer sections to move as a unit. This is of considerable importance since it causes the uniform displacement of each of the spiral grooves 33 and a corresponding uniform displacement of the grinding elements whereby the latter, regardless of their relative radial position, are, at all times, held at constant radii from 1 the axis of the member to be ground.

Thus, where the surface i2, is out of round, the grinding elements, notwithstanding the inward pressure applied thereagainst, will not follow the out of round contour of the surface, but will, at all times, be maintained in a fixed circular position with the result that the elements are held out of engagement with the low spots" of the surface and are effective to reduce only the high spots whereby the surface will be brought into substantially perfect roundness with a minimum removal of material. To further assist the proper grinding of the "high spots of the surface and to more effectively prevent the elements from advancing into the low spots, the grinding face of the elements are preferably of considerable material adjacent the central portion of the pin caused by the longitudinal movement of the device thereover, the abrasive blocks 29, as will be clear from Figure 5, are preferably arranged to provide an increased grinding area adjacent the longitudinal ends 54 and 56 of the grinding elements.

Preferably the section I6 is provided with a plurality of set screws 5Iwhich are engageable with the body portions 26 of the grinding elements to lock these members in adjusted position to permit truing of the faces of the blocks 29 to different curvatures for grinding surfaces of different diameters. While the grinding elements will at all times during rotation around a surface being' ground, be urged toward such surface by reason of the pitch of the guides as above explained, the force of the elements against the surfacemay be,-in-,-] creased by and atzthe will-ofthedperatonFby manually retarding the rotation of the 'innery' section 16. This-may obviously be done in various ways. For example, the operator may hold a tool or. thelikeagainst the side'of the section to cause the heads of screws 51 to strike suchtool and to thus shift the section l6 slightly with I respect to section I! to advance the grinding elements against the surface being ground. U

"I claim: a l 1. A device for grinding an exterior 'surface comprising, a member adapted to rotate around said surface, a grinding element carried by said -member and engageable with said surface, and

means operated by the friction of said element on '1 said surface upon rotation of said member to urge said element against said surface.

2. A device for grinding cylindrical surfaces or the like comprising, a ring member composed of annular sections movable relative to each other and adapted for mounting with its axis substantially coincident with the axis of said surface, one of said sections being adapted for rotation, a grinding element carried by said other section for engagement with said surface, and means connecting said last named section with said other section for rotation therewith and effective incident to such rotation and engagement of said element with said surface to urge said element against said surface.

3. A device for grinding cylindrical surfaces or the like comprising, a ring member composed of annular sections movable relative to each other and adapted for mounting with its axis substantially coincident with the axis of said surface, one of said sections being adapted for rotation, a plurality of grinding elements carried by said other section for engagement with said surfaces, cam means connecting said elements with said first section and actuated by a rotative force differential between said sections in one direction to urge said elements against said surface, and means preventing a retraction of said elements from said surface incident to a rotative force diiferential between the sections in a reverse direction.

4. A device for grinding cylindrical surfaces or the like comprising, a ring member composed of annular sections movable relative to each other and adapted for mounting with its axis substantially coincident with the axis of said surface, one of said sections being adapted for rotation, a plurality of grinding elements carried bysaid other section for engagement with said surfaces. cam means connecting said elements with. said first section and actuated by a rotative force differential between said sections in one direction to urge said elements against said surface, and means operated upon rotation of said sections for locking the same against relative displacement incident to the application of rotative force diiferential in an opposite direction .and releasing said sections for displacement when stationary, and a key providing a relative movement between said sections when stationary for adjusting the radial position of said grinding elements.

5. A device for grinding an exterior cylindrical surface comprising, a ring member having a removable circumferential portion to enable positioning of said member around a surface to be ground and being adapted for rotation around said surface, a plurality of elements carried by said member in circumferentially spaced relation and movable radially thereof into engagement with said surface for supporting said member in concentric position on said surafce and effective to grind said surface on rotation thereof with said member around said surface, and means operative during said rotation to simultaneously advance said elements at constant radii towards said surface and hold said elements against individual retraction from said surface.

6. A device for grinding an exterior cylindrical surface comprising, a sectional ring support adapted for opening and assembling around a cylindrical surface to be ground and including, an annular drive member, and an annular driven member, means carried by said support and engageable with said surface to center said support around said surface and effective to grind said surface on rotation of said support therearound, and means operative upon a relative displacement of said drive and driven members to advance said first means against said surface.

ALBERT J. SEVERE, Jl. 

